Persistence of Herbicide Residues in Gammarus Lacustris (crustacea: Amphipoda) in Prairie Wetlands

Tandem mass spectrometry (MS) was used to detect herbicide residues in wild populations of amphipods collected from microcosms spiked with a single pulse of either Avadext-BW (triallate) or HoeGrasst (diclofop-methyl) at three different concentrations (1.0, 10.0, and 100.0 mg·L21). Independent confirmations of both herbicides were obtained by spiking amphipod tissues with 50 pg of authentic standards of triallate or diclofop-acid. The in situ microcosm experiments demonstrated that positive confirmation of triallate could still be made 30 d following an initial single spike of 10 mg·L21 triallate. Diclofop-acid could still be detected in lipidrich tissues of amphipods 10 and 15 d following an initial spike concentration of 10 and 100 mg·L21, respectively. The chief advantages of tandem MS include the ability to analyze small quantities of tissue (,1 mg wet weight), the ability to detect picogram levels of target analytes, and user flexibility in the choice of tissue to be analyzed (e.g., lipid-rich storage tissue, muscle, nervous tissue, etc.). Keywords—Persistence Amphipods Herbicides Mass spectrometry Lipids